MENIFEE, Calif. - The 16-year-old brother of an 11-year-old autistic boy who disappeared over the weekend from his Southern California home was arrested Wednesday on a murder charge, police said.

During a news conference Wednesday, Capt. John Hill said the body of a boy who fits the description of 11-year-old Terry Smith was found overnight in a "shallow grave containing partially exposed human remains."

Investigators were still working to confirm the identity of the remains found Wednesday afternoon.

John Hall, a spokesman the Riverside County District Attorney has not returned phone or email messages from The (Palm Springs, Calif.) Desert Sun.

The teen, whose name was not released, was the last one to see Terry near his Menifee, Calif., home Saturday, the Riverside County Sheriff's Department previously said.

"The brother was walking away from their residence, turns back, sees that Terry's following him and tells Terry, 'Hey, go home,'" Deputy Albert Martinez told The Desert Sun this week.

The half-bother - who has the same mom as Terry - has been "questioned several times by investigators," Martinez said Tuesday afternoon.

"He's been cooperative throughout the whole time," the deputy said.

Earlier Wednesday, investigators halted their search and returned to Terry's home to search for human remains at about 1:30 a.m.

It was the fourth day of a widespread search for the boy, who was identified by police as an autistic boy who was last seen Saturday.

Investigators found "possible human remains" in the dirt not far from the house, and a search warrant was issued at the house late Wednesday morning, said Sgt. Lisa McConnell.

Investigators initially said that Terry "was discovered missing from his residence" sometime between 7:30 p.m. Saturday and 10:30 a.m. Sunday.

Terry lived on a short stretch of road in a rural area of Menifee, a city of about 80,000 in southwestern Riverside County, Calif., that is about 80 miles southeast of Los Angeles.

They were "able to verify" Monday that Terry was last seen between 7:30 and 9 p.m. Saturday outside his home, McConnell said.

As the search went on and temperatures peaked above 100 degrees each day, more than 1,000 law enforcement, search and rescue personnel and volunteers flooded into the city to help search.

Searchers canvassed by ATV, bicycle and foot and distributed thousands of fliers. Coordinators set up a Find Terry Smith page on Facebook that garnered more than 25,000 fans.

The volunteer coordinators initially held out hope they would find Terry but announced they called off the search and would now enter a "time of grieving."

"We want to thank everyone who is following our efforts here and for the thousands of volunteers and businesses that have helped this incredible search effort," the page administrator posted Wednesday.

"PLEASE REMEMBER that our focus has always been on Terry Smith, an 11 year old boy. Our focus is still on that boy and the memory."